A hydraulic brake device for transmitting the operated quantity of the brake pedal to the spool of the hydraulic device through a link to increase the breaking power is disclosed in, for example, Japanese Patent Laid-Open No. H5-124492.
A hydraulic booster generally has large weight, and a booster of a bonnet-type truck is positioned inside the engine room. The engine room can endure the weight of the booster since a chassis frame is positioned underneath the floor. Therefore, the booster is operated directly via a push rod from the pedal inside the cab room. In a forward control vehicle, the booster can't be mounted underneath the floor of the cab since the floor can't endure such weight. Considering the hydraulic piping from the hydraulic booster to the brake of each wheel, it is preferable that the hydraulic booster of a forward control vehicle be placed on the chassis frame of the vehicle.
In a forward control vehicle having a cab positioned on the chassis frame of the vehicle, the cab is mounted on the frame with a tilt structure so that the cab can tilt against the frame. Further, the cab is mounted on the frame through a suspension.
The brake pedal is positioned inside the cab, so a device for transmitting the operated quantity of the brake pedal accurately to the spool of the hydraulic booster is necessary.
In a forward control vehicle, the movement of the cab against the frame differs from the movement of the cab against the chassis at the time of driving, so the cab suspension is displaced relatively, and the cab may be tilted by the tilt structure.
The present invention provides a hydraulic brake device to be applied to a forward control vehicle described above comprising a device having a means for absorbing the relative displacement between the cab and the chassis.